1. Field of the Invention
The present invention relates to a central management apparatus for managing devices (image forming apparatuses and the like) connected to device management units through data communication with the various management units.
2. Description of the Related Art
Management systems are known which batch manage at a center apparatus the devices (image forming apparatuses and the like) connected to each device management unit by a connecting device management unit for data collection and the like to an image forming apparatus and executing data communication between the central management apparatus and the plurality of device management units.
In this management system, time for communication between the device management units and the central management apparatus is allocated to each device management unit avoiding duplication so as to provide data communication between the central management apparatus and the plurality of device management units to avoid congestion of communication traffic. Furthermore, in this management system, the device management units are constructed so as to transmission the central management apparatus to communicate when trouble occurs in an image forming apparatus and not only to transmit collected data periodically to the central management apparatus. Furthermore, the central management device determines [no reception] when a device management unit has not sent data (normal data transmission other than a trouble data) at a set time after the allotted time has elapsed, deems some trouble to have occurred, and executes a trouble response.
Known communication means used by the management system include the method of sending/receiving data while apparatuses at both ends (device management unit and central management apparatus) maintain a communication line connection (telephone, facsimile and the like) (i.e., methods using a public telephone network), and the method wherein electronic mail (internet mail (packet data)) transmitted from one apparatus is received by the other apparatus through a plurality of computers.
When the central management device determines [no reception] when a device management unit has not sent data at a set time after the allotted by the management system time has elapsed, the [no reception] state is not determined immediately after the allotted time has elapsed, but rather the [no reception] state is determined when data transmission has not occurred after a certain allowed time has elapsed after the allotted time.
The previously mentioned method using a public telephone network and method using electronic mail are communication means, and both methods have differences as to the causes delaying data of the set time. That is, in the former method a cause may be that a connection cannot be made because another device is using the line, whereas in the latter method, in relation to reliable delivery of the data at the center after the connection is made, reception of the transmission may be delayed because one of the intervening computers goes down while the transmission is in transit even though transmission occurred within the fixed time.
Accordingly, when considering a management system comprising a central management apparatus connected to a plurality of device management units respectively provided with different communication means, there is the problem of setting the allowable time when determining [no reception]. That is, when the allowable time is set in consideration of the characteristics of the former communication means, there are many occurrences of [no reception] regardless of normal data transmission by device management units provided with the latter communication means, thereby producing needless counter measure response by the central management apparatus, and increasing the confusion arising from such needless response. On the other hand, when the allowable time is set in consideration of the characteristics of the latter communication means, there are frequent delays in determining [no reception] of device management units provided with the former communication means, and as a result there are many delays in suitable response by the central management apparatus.